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- Bill Jackson, Kiyoshi Yoshimoto
- Journal of Graph Theory
- 2009

By Petersen's theorem, a bridgeless cubic graph has a 2-factor. H. Fleis-chner extended this result to bridgeless graphs of minimum degree at least three by showing that every such graph has a spanning even subgraph. Our main result is that, under the stronger hypothesis of 3-edge-connectivity, we can find a spanning even subgraph in which every component… (More)

- Kiyoshi Yoshimoto
- Discrete Mathematics
- 2007

- Atsushi Kaneko, Mikio Kano, Kiyoshi Yoshimoto
- Int. J. Comput. Geometry Appl.
- 2000

Given an integer λ ≥ 2, a graph G = (V, E) and a spanning subgraph H of G (the backbone of G), a λ-backbone coloring of (G, H) is a proper vertex coloring V → {1, 2,. . .} of G, in which the colors assigned to adjacent vertices in H differ by at least λ. We study the case where the backbone is either a collection of pair-wise disjoint stars or a matching.… (More)

- Atsushi Kaneko, Kiyoshi Yoshimoto
- Journal of Graph Theory
- 2003

- Bill Jackson, Kiyoshi Yoshimoto
- Discrete Mathematics
- 2007

By Petersen's theorem, a bridgeless cubic multigraph has a 2-factor. H. Fleischner generalised this result to bridgeless multigraphs of minimum degree at least three by showing that every such multigraph has a spanning even sub-graph. Our main result is that every bridgeless simple graph with minimum degree at least 3 has a spanning even subgraph in which… (More)

- Hajo Broersma, Daniël Paulusma, Kiyoshi Yoshimoto
- Graphs and Combinatorics
- 2009

Let G be a claw-free graph with order n and minimum degree δ. We improve results of Faudree et al. and Gould & Jacobson, and solve two open problems by proving the following two results. If δ = 4, then G has a 2-factor with at most (5n − 14)/18 components, unless G belongs to a finite class of exceptional graphs. If δ ≥ 5, then G has a 2-factor with at most… (More)

- Yoshimi Egawa, Haruhide Matsuda, Tomoki Yamashita, Kiyoshi Yoshimoto
- Graphs and Combinatorics
- 2008

Let k ≥ 2 be an integer. We show that if G is a (k + 1)-connected graph and each pair of nonadjacent vertices in G has degree sum at least |G| + 1, then for each subset S of V (G) with |S| = k, G has a spanning tree such that S is the set of endvertices. This result generalizes Ore's theorem which guarantees the existence of a Hamilton path connecting any… (More)

- Jun Fujisawa, Liming Xiong, Kiyoshi Yoshimoto, Shenggui Zhang
- Journal of Graph Theory
- 2007

Let G be a simple graph with order n and minimum degree at least two. In this paper, we prove that if every odd branch-bond in G has an edge-branch, then its line graph has a 2-factor with at most 3n−2 8 components. For a simple graph with minimum degree at least three also, the same conclusion holds.

- Ralph J. Faudree, Colton Magnant, Kenta Ozeki, Kiyoshi Yoshimoto
- Journal of Graph Theory
- 2012

In this article, we prove that a line graph with minimum degree δ ≥ 7 has a spanning subgraph in which every component is a clique of order at least three. This implies that if G is a line graph with δ ≥ 7, then for any independent set S there is a 2-factor of G such that each cycle contains at most one vertex of S. This supports the conjecture that δ ≥ 5… (More)